Cyclodepsipeptides with antineoplastic activity and methods of using to inhibit cancer and microbial growth

ABSTRACT

The present invention is directed to cyclodepsipeptide compounds having antineoplastic and/or antimicrobial activity, preferably Kitastatin 1. The present invention is further directed to methods of inhibiting cancer cell growth and/or microbial growth in a host inflicted therewith by administering cyclodepsipeptide compounds to the inflicted host.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application is a continuation of application Ser. No.12/598,943, which was filed on Apr. , 2010, now U.S. Pat. No. 8,415,294,issued on Apr. 9, 2013, which was filed pursuant to 35 U.S.C. 371 as aU.S. National Phase application of International Patent Application No.PCT/US08/65976, which was filed Jun. 5, 2008, claiming the benefit ofpriority to U.S. Patent Application No. 60/942,058, which was filed onJun. 5, 2007. The entire text of the aforementioned applications isincorporated herein by reference in its entirety.

STATEMENT OF FEDERALLY SPONSORED RESEARCH

Financial assistance for this invention was provided by the UnitedStates Government, through the Division of Cancer Treatment andDiagnosis, National Cancer Institute, DHHS by Outstanding InvestigatorGrant CA44344-03-12 and RO1 CA90441-01-05. Therefore, the United StatesGovernment may own certain rights to this invention.

FIELD OF THE INVENTION

The present invention is directed to cyclodepsipeptide compounds havingantineoplastic and/or antimicrobial activity. The present invention isfurther directed to methods of inhibiting cancer cell growth and/ormicrobial growth in a host inflicted therewith by administeringcyclodepsipeptide compounds to the inflicted host.

BACKGROUND OF THE INVENTION

The actinomycete genus Kitasatospora has a developing history ofproducing biologically active metabolites, especially those with cancercell growth inhibitory properties. An early example of the latter wasthe isolation of the anticancer antibiotic terpentecin from a soilKitasatospora sp. (strain MF730-N6) by Umezawa and colleagues in 1985.²That advance was quickly followed by the isolation of anticancercarbolines from Kitasatospora setae ^(3a,b) cultured from a Spitsbergensoil sample.⁴ In 1993, the stereochemically undefined cyclodepsipeptiderespirantin (1) was isolated from a Kitasatospora sp. during anexamination of its constituents for insecticidal activity.⁵Interestingly, in an investigation of endophytic actinomycetes on Taxusbaccata plants, a Kitasatospora sp. (strain P & U 22869) was isolatedand found to produce taxol and related taxanes.⁶ More recently,Kitasatospora spp. have been found to produce yeast-like pleiotropicdrug-resistant pump constituents,⁷ proteasome inhibitors designatedtyropeptins A and B,⁸ and bafilomycin-like antifungal compounds⁹; morerecently, K. cheerisanensis was found to contain the cytotoxicbafilomycin C1-amide.¹⁰ The bafilomycins represent a group of16-membered macrocyclic lactones isolated from K. setae and severalstreptomyces species and are very strong cancer-cell-growthinhibitors.^(11a-h)

SUMMARY OF THE INVENTION

The present invention is directed to novel cyclodepsipeptide compounds.Preferably, the compound is in a substantially pure form having thestructural formula

and more preferably, the compound is denominated as Kitastatin 1 havingthe structural formula:

In one embodiment the compound is in a pharmaceutically acceptablecarrier. Preferably, the compound is in a therapeutically effectiveamount sufficient to inhibit cancer cell growth or to inhibit the growthof a parasitic microbe.

The present invention is further directed methods of inhibiting cancercell growth in a host inflicted therewith by administering acyclodepsipeptide compound to the inflicted host. Preferably, the hostis a human and the method comprises administering to the host atherapeutically effective amount of a compound having the structuralformula:

or salts thereof, wherein

R₁ is CH₂CH(CH₃)₂ or CH(CH₃)₂; and

R₂ is CHO or H.

In one nonlimiting embodiment, R₁ is CH₂CH(CH₃)₂ and R₂ is H. Morepreferably, the compound has the structural formula:

The compounds can be administered alone or more preferably the compoundis administered in a pharmaceutically acceptable carrier.

In a preferred embodiment, the method is used to inhibit the growth ofone or more cancer cells selected from the group consisting of:leukemia, pancreas, breast, CNS, lung-NSC, colon, or prostate cancer.

The compounds of the present invention can advantageously be used toinhibit microbial growth. In one embodiment, the invention is directedto a method of inhibiting microbial growth. The method preferablycomprises contacting a microbe with a therapeutically effective amountof a compound of the invention. The compound used can be one or morecyclodepsipeptide compounds or salts thereof in an amount sufficient toinhibit the microbial growth. Preferably the compound used to inhibitmicrobial growth has the structural formula:

wherein

R₁ is CH₂CH(CH₃)₂ or CH(CH₃)₂; and

R₂ is CHO or H.

One preferred compound having anti-microbial growth activity has thefollowing structural formula:

In one embodiment, the step of contacting the microbe with the compoundis accomplished by administering the compound to a host infected withthe microbe. Advantageously, the host is preferably a human and thecompound used inhibits the growth of at least one of the followingmicrobes: Cryptococcus neoformans, Enerococus faecalis, Micrococcusluteus, Stenotrophomonas maltophilia, Micrococcus luteus, Staphylococcusaureus, Escherichia coli, Enterobacter cloacae, Steptococcus pneumoniae,Neisseria gonorrhoeae, or Candida albicans; and, more preferably, atleast Cryptococcus neoformans, Enerococus faecalis, or Micrococcusluteus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows cyclodepsipeptides 1-3, wherein cyclodepsipeptide 1 isrespirantin, cyclodepsipeptide 2 is a valeryl homologue, andcyclodepsipeptide 3 is kitastatin 1.

DETAILED DESCRIPTION OF THE INVENTION

As described above, the present invention is directed to novelcyclodepsipeptide compounds. Reference to a compound of the inventionherein is understood to include reference to salts thereof, unlessotherwise indicated. The term “salt(s)”, as employed herein, denotesacidic and/or basic salts formed with inorganic and/or organic acids andbases. Salts of the compounds of the invention may be formed, forexample, by reacting the compound with an amount of acid or base, suchas an equivalent amount, in a medium such as one in which the saltprecipitates or in an aqueous medium followed by lyophilization.Formation of salts is well within the ability of one skilled in the art.Examples of specific salts of the compound of the invention are providedherein, but are not intended to be limiting.

Preferred compounds of the invention inhibit the growth of cancer cellsand/or parasitic microbial growth. Preferably, the compound inhibitscancer cells, and more preferably the compounds inhibit one or morecancer cells selected from the group consisting of leukemia, pancreas,breast, CNS, lung-NSC, colon, or prostate cancer.

In another embodiment, a method is provided for inhibiting the growth ofcancer cells in a host. The method comprises administering to a hostinflicted with cancer at least one cyclodepsipeptide compound disclosedherein. Preferably, the compound is administered in a pharmaceuticalcomposition. Preferred pharmaceutical compositions are discussed indetail below. The compound administered is typically in atherapeutically effective amount sufficient to inhibit the cancer cellgrowth in the host. The host is preferably an animal, more preferably amammal, and most preferably a human.

In certain embodiments, the method comprises administering to a host inneed thereof an effective amount of a compound of the invention and atleast one additional therapeutic agent. In one embodiment, theadditional therapeutic agent is a chemotherapeutic agent including, butnot limited to, methotrexate, taxol, mercaptopurine, thioguanine,hydroxyurea, cytarabine, cyclophosphamide, ifosfamide, nitrosoureas,cisplatin, carboplatin, mitomycin, dacarbazine, procarbizine,etoposides, campathecins, bleomycin, doxorubicin, idarubicin,daunorubicin, dactinomycin, plicamycin, mitoxantrone, asparaginase,vinblastine, vincristine, vinorelbine, paclitaxel, docetaxel, andmixtures thereof.

In another embodiment, the invention is directed to a method ofinhibiting microbial growth, preferably in a host as described above.The method comprises administering to a host at least onecyclodepsipeptide compound disclosed herein in a therapeuticallyeffective amount sufficient to inhibit the microbial growth in the host.The compounds of invention can be administered, alone or in combinationwith one or more additional antimicrobial agents, to treat microbialinfections such as fungal infections and bacterial infections, orcombinations of such infections.

Accordingly, in one specific embodiment the invention is a method fortreating a microbial infection wherein the fungal infection is resistantto, or sensitive to, an azole antifungal agent, such as fluconazole. Themethods of the invention may further include co-administration of asecond antimicrobial agent, resulting in administration of an additionalantifungal agent and/or an antibacterial agent.

Fungal infections include fungal infections (mycoses), which may becutaneous, subcutaneous, or systemic. Superficial mycoses include tineacapitis, tinea corporis, tinea pedis, onychomycosis, perionychomycosis,pityriasis versicolor, oral thrush, and other candidoses such asvaginal, respiratory tract, biliary, eosophageal, and urinary tractcandidoses. Systemic mycoses include systemic and mucocutaneouscandidosis, cryptococcosis, aspergillosis, mucormycosis (phycomycosis),paracoccidioidomycosis, North American blastomycosis, histoplasmosis,coccidioidomycosis, and sporotrichosis. Fungal infections includeopportunistic fungal infections, particularly in immunocompromisedpatients such as those with AIDS. Fungal infections contribute tomeningitis and pulmonary or respiratory tract diseases.

Pathogenic organisms include dermatophytes (e.g., Microsporum canis andother M. spp.; and Trichophyton spp. such as T. rubrum, and T.mentagrophytes), yeasts (e.g., Candida albicans, C. Tropicalis, or otherCandida species), Torulopsis glabrata, Epidermophyton floccosum,Malassezia fuurfur (Pityropsporon orbiculare, or P. ovale), Cryptococcusneoformans, Aspergillus fumigatus, and other Aspergillus spp.,Zygomycetes (e.g., Rhizopus, Mucor), Paracoccidioides brasiliensis,Blastomyces dermatitides, Histoplasma capsulatum, Coccidioides immitis,and Sporothrix schenckii. Fungal infections include Cladosporiumcucumerinum, Epidermophyton floccosum, and Microspermum ypseum. Examplesof current antimycotic drugs include nystatin, clotrimazole,amphotericin B, ketoconazole, fluconazole, and itraconazole.

Bacterial infections result in diseases such as bacteremia, pneumonia,meningitis, osteomyelitis, endocarditis, sinusitis, arthritis, urinarytract infections, tetanus, gangrene, colitis, acute gastroenteritis,bronchitis, and a variety of abscesses, nosocomial infections, andopportunistic infections. Bacterial pathogens include Gram-positivecocci such as Staphylococcus aureus, Streptococcus pyogenes (group A),Streptococcus spp. (viridans group), Streptococcus agalactiae (group B),S. bovis, Streptococcus (anaerobic species), Streptococcus pneumoniae,and Enterococcus spp.; Gram-negative cocci such as Neisseriagonorrhoeae, Neisseria meningitidis, and Branhamella catarrhalis;Gram-positive bacilli such as Bacillus anthracis, Corynebacteriumdiphtheriae and Corynebacterium species which are diptheroids (aerobicand anerobic), Listeria monocytogenes, Clostridium tetani, Clostridiumdifficile, Escherichia coli, Enterobacter species, Proteus mirablis andother spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella,Shigella, Serratia, and Campylobacter jejuni.

Preferably, the compound used inhibits a microbe from the genusNeisseria, Enterococcus, Streptococcus or Cryptococcus and even morepreferably the compound inhibits a microbe selected from the groupconsisting of: Neisseria gonorrhoeae; Enterococcus faecalis;Streptococcus pneumoniae; and Cryptococcus neoformans.

Pharmaceutical Compositions and Dosage Forms

Pharmaceutical compositions can be used in the preparation of individualdosage forms. Consequently, pharmaceutical compositions and dosage formsof the invention comprise the active ingredients disclosed herein. Thenotation of “active ingredient” signifies the compounds of the inventiondescribed herein or salts thereof. Pharmaceutical compositions anddosage forms of the invention can further comprise a pharmaceuticallyacceptable carrier.

In one embodiment, the term “pharmaceutically acceptable” means approvedby a regulatory agency of the Federal or a state government or listed inthe U.S. Pharmacopeia or other generally recognized pharmacopeia for usein animals, and more particularly in humans. The term “carrier” refersto a diluent, adjuvant, excipient, or vehicle with which an activeingredient is administered. Such pharmaceutical carriers can be liquids,such as water and oils, including those of petroleum, animal, vegetableor synthetic origin, such as peanut oil, soybean oil, mineral oil,sesame oil and the like. The pharmaceutical carriers can be saline, gumacacia, gelatin, starch paste, talc, keratin, colloidal silica, urea,and the like. In addition, other excipients can be used.

Single unit dosage forms of the invention are suitable for oral, mucosal(e.g., nasal, sublingual, vaginal, buccal, or rectal), parenteral (e.g.,subcutaneous, intravenous, bolus injection, intramuscular, orintraarterial), or transdermal administration to a patient. Examples ofdosage forms include, but are not limited to: tablets; caplets;capsules, such as soft elastic gelatin capsules; cachets; troches;lozenges; dispersions; suppositories; ointments; cataplasms (poultices);pastes; powders; dressings; creams; plasters; solutions; patches;aerosols (e.g., nasal sprays or inhalers); gels; liquid dosage formssuitable for oral or mucosal administration to a patient, includingsuspensions (e.g., aqueous or non-aqueous liquid suspensions,oil-in-water emulsions, or a water-in-oil liquid emulsions), solutions,and elixirs; liquid dosage forms suitable for parenteral administrationto a patient; and sterile solids (e.g., crystalline or amorphous solids)that can be reconstituted to provide liquid dosage forms suitable forparenteral administration to a patient.

The composition, shape, and type of dosage forms of the invention willtypically vary depending on their use. For example, a dosage form usedin the acute treatment of a neoplastic disease or microbial infectionmay contain larger amounts of one or more of the active ingredients itcomprises than a dosage form used in the chronic treatment of the samedisease. Similarly, a parenteral dosage form may contain smaller amountsof one or more of the active ingredients it comprises than an oraldosage form used to treat the same disease. These and other ways inwhich specific dosage forms encompassed by this invention will vary fromone another will be readily apparent to those skilled in the art. See,e.g., Remington's Pharmaceutical Sciences, 18th ed., Mack Publishing,Easton Pa. (1990).

Typical pharmaceutical compositions and dosage forms comprise one ormore excipients. Suitable excipients are well known to those skilled inthe art of pharmacy, and non-limiting examples of suitable excipientsare provided herein. Whether a particular excipient is suitable forincorporation into a pharmaceutical composition or dosage form dependson a variety of factors well known in the art including, but not limitedto, the way in which the dosage form will be administered to a patient.For example, oral dosage forms such as tablets may contain excipientsnot suited for use in parenteral dosage forms. The suitability of aparticular excipient may also depend on the specific active ingredientsin the dosage form. For example, the decomposition of some activeingredients may be accelerated by some excipients such as lactose, orwhen exposed to water.

The invention further encompasses pharmaceutical compositions and dosageforms that comprise one or more compounds that reduce the rate by whichan active ingredient will decompose. Such compounds, which are referredto herein as “stabilizers,” include, but are not limited to,antioxidants such as ascorbic acid, pH buffers, or salt buffers.

As used herein, a “therapeutically effective amount” is an amountsufficient to either inhibit (partially or totally) formation of a tumoror a hematological malignancy or to reduce its further progression or toinhibit the growth of a microbe of interest. For a particular conditionor method of treatment, the dosage is determined empirically, usingknown methods, and will depend upon facts such as the biologicalactivity of the particular compound employed, the means ofadministrations, the age, health and body weight of the host; the natureand extent of the symptoms, the frequency of treatment; theadministration of other therapies and the effect desired. Hereinafterare described various possible dosages and methods of administrationwith the understanding that the following are intended to beillustrative only. The actual dosages and method of administration ordelivery may be determined by one of skill in the art.

Typical illustrative dosage forms of the invention comprise a compoundor mixture of compounds of the invention thereof as an active ingredientin an amount of from about 1 mg to about 2000 mg, more preferably fromabout 25 mg to about 1000 mg, even more preferably from about 50 mg toabout 750 mg, and most preferably from about 100 mg to about 500 mg.

For illustrative purposes, dosage levels of the administered activeingredients may be: intravenous, 0.01 to about 20 mg/kg; intramuscular,0.1 to about 50 mg/kg; orally, 0.05 to about 100 mg/kg; intranasalinstillation, 0.5 to about 100 mg/kg; and aerosol, 0.5 to about 100mg/kg of host body weight.

Expressed in terms of concentration, an active ingredient may be presentin the compositions of the present invention for localized use about thecutis, intranasally, pharyngolaryngeally, bronchially, intravaginally,rectally, or ocularly in concentration of from about 0.01 to about 50%w/w of the composition; preferably about 1 to about 20% w/w of thecomposition; and for parenteral use in a concentration of from about0.05 to about 50% w/v of the composition and preferably from about 5 toabout 20% w/v.

The active ingredients to be employed as antineoplastic or antimicrobialagents can be easily prepared in such unit dosage form with theemployment of pharmaceutical materials which themselves are available inthe art and can be prepared by established procedures. The followingpreparations are illustrative of the preparation of dosage forms of thepresent invention, and not as a limitation thereof.

Oral Dosage Forms

Pharmaceutical compositions of the invention that are suitable for oraladministration can be presented as discrete dosage forms, such as, butare not limited to, tablets (e.g., chewable tablets), caplets, capsules,and liquids (e.g., flavored syrups). Such dosage forms containpredetermined amounts of active ingredients, and may be prepared bymethods of pharmacy well known to those skilled in the art. Seegenerally, Remington's Pharmaceutical Sciences, 18th ed., MackPublishing, Easton Pa. (1990).

Typical oral dosage forms of the invention are prepared by combining theactive ingredients in an intimate admixture with at least one excipientaccording to conventional pharmaceutical compounding techniques.Excipients can take a wide variety of forms depending on the form ofpreparation desired for administration. For example, excipients suitablefor use in oral liquid or aerosol dosage forms include, but are notlimited to, water, glycols, oils, alcohols, flavoring agents,preservatives, and coloring agents. Examples of excipients suitable foruse in solid oral dosage forms (e.g., powders, tablets, capsules, andcaplets) include, but are not limited to, starches, sugars,micro-crystalline cellulose, diluents, granulating agents, lubricants,binders, and disintegrating agents.

Because of their ease of administration, tablets and capsules representthe most advantageous oral dosage unit forms, in which case solidexcipients are employed. If desired, tablets can be coated by standardaqueous or nonaqueous techniques. Such dosage forms can be prepared byany of the methods of pharmacy. In general, pharmaceutical compositionsand dosage forms are prepared by uniformly and intimately admixing theactive ingredients with liquid carriers, finely divided solid carriers,or both, and then shaping the product into the desired presentation ifnecessary.

For example, a tablet can be prepared by compression or molding.Compressed tablets can be prepared by compressing in a suitable machinethe active ingredients in a free-flowing form such as powder orgranules, optionally mixed with an excipient. Molded tablets can be madeby molding in a suitable machine a mixture of the powdered compoundmoistened with an inert liquid diluent.

Examples of excipients that can be used in oral dosage forms of theinvention include, but are not limited to, binders, fillers,disintegrants, and lubricants. Binders suitable for use inpharmaceutical compositions and dosage forms include, but are notlimited to, corn starch, potato starch, or other starches, gelatin,natural and synthetic gums such as acacia, sodium alginate, alginicacid, other alginates, powdered tragacanth, guar gum, cellulose and itsderivatives (e.g., ethyl cellulose, cellulose acetate, carboxymethylcellulose calcium, sodium carboxymethyl cellulose), polyvinylpyrrolidone, methyl cellulose, pre-gelatinized starch, hydroxypropylmethyl cellulose, (e.g., Nos. 2208, 2906, 2910), microcrystallinecellulose, and mixtures thereof.

Suitable forms of microcrystalline cellulose include, but are notlimited to, the materials sold as AVICEL-PH-101, AVICEL-PH-103 AVICELRC-581, AVICEL-PH-105 (available from FMC Corporation, American ViscoseDivision, Avicel Sales, Marcus Hook, Pa.), and mixtures thereof. Aspecific binder is a mixture of microcrystalline cellulose and sodiumcarboxymethyl cellulose sold as AVICEL RC-581. Suitable anhydrous or lowmoisture excipients or additives include AVICEL-PH-103.TM and Starch1500 LM.

Examples of fillers suitable for use in the pharmaceutical compositionsand dosage forms disclosed herein include, but are not limited to, talc,calcium carbonate (e.g., granules or powder), microcrystallinecellulose, powdered cellulose, dextrates, kaolin, mannitol, silicicacid, sorbitol, starch, pre-gelatinized starch, and mixtures thereof.The binder or filler in pharmaceutical compositions of the invention istypically present in from about 50 to about 99 weight percent of thepharmaceutical composition or dosage form.

Disintegrants are used in the compositions of the invention to providetablets that disintegrate when exposed to an aqueous environment.Tablets that contain too much disintegrant may disintegrate in storage,while those that contain too little may not disintegrate at a desiredrate or under the desired conditions. Thus, a sufficient amount ofdisintegrant that is neither too much nor too little to detrimentallyalter the release of the active ingredients should be used to form solidoral dosage forms of the invention. The amount of disintegrant usedvaries based upon the type of formulation, and is readily discernible tothose of ordinary skill in the art. Typical pharmaceutical compositionscomprise from about 0.5 to about 15 weight percent of disintegrant,preferably from about 1 to about 5 weight percent of disintegrant.

Disintegrants that can be used in pharmaceutical compositions and dosageforms of the invention include, but are not limited to, agar-agar,alginic acid, calcium carbonate, microcrystalline cellulose,croscarmellose sodium, crospovidone, polacrilin potassium, sodium starchglycolate, potato or tapioca starch, other starches, pre-gelatinizedstarch, other starches, clays, other algins, other celluloses, gums, andmixtures thereof.

Lubricants that can be used in pharmaceutical compositions and dosageforms of the invention include, but are not limited to, calciumstearate, magnesium stearate, mineral oil, light mineral oil, glycerin,sorbitol, mannitol, polyethylene glycol, other glycols, stearic acid,sodium lauryl sulfate, talc, hydrogenated vegetable oil (e.g., peanutoil, cottonseed oil, sunflower oil, sesame oil, olive oil, corn oil, andsoybean oil), zinc stearate, ethyl oleate, ethyl laureate, agar, andmixtures thereof. Additional lubricants include, for example, a syloidsilica gel (AEROSIL 200, manufactured by W.R. Grace Co. of Baltimore,Md.), a coagulated aerosol of synthetic silica (marketed by Degussa Co.of Plano, Tex.), CAB-O-SIL (a pyrogenic silicon dioxide product sold byCabot Co. of Boston, Mass.), and mixtures thereof. If used at all,lubricants are typically used in an amount of less than about 1 weightpercent of the pharmaceutical compositions or dosage forms into whichthey are incorporated.

A preferred solid oral dosage form of the invention comprises an activeingredient, anhydrous lactose, microcrystalline cellulose,polyvinylpyrrolidone, stearic acid, colloidal anhydrous silica, andgelatin.

Delayed Release Dosage Forms

Active ingredients of the invention can be administered by controlledrelease means or by delivery devices that are well known to those ofordinary skill in the art. Examples include, but are not limited to,those described in U.S. Pat. Nos. 3,845,770; 3,916,899; 3,536,809;3,598,123; and 4,008,719, 5,674,533, 5,059,595, 5,591,767, 5,120,548,5,073,543, 5,639,476, 5,354,556, and 5,733,566, each of which isincorporated herein by reference. Such dosage forms can be used toprovide slow or controlled-release of one or more active ingredientsusing, for example, hydropropylmethyl cellulose, other polymer matrices,gels, permeable membranes, osmotic systems, multilayer coatings,microparticles, liposomes, microspheres, or a combination thereof toprovide the desired release profile in varying proportions. Suitablecontrolled-release formulations known to those of ordinary skill in theart, including those described herein, can be readily selected for usewith the active ingredients of the invention. The invention thusencompasses single unit dosage forms suitable for oral administrationsuch as, but not limited to, tablets, capsules, gelcaps, and capletsthat are adapted for controlled-release.

All controlled-release pharmaceutical products have a common goal ofimproving drug therapy over that achieved by their non-controlledcounterparts. Ideally, the use of an optimally designedcontrolled-release preparation in medical treatment is characterized bya minimum of drug substance being employed to cure or control thecondition in a minimum amount of time. Advantages of controlled-releaseformulations include extended activity of the drug, reduced dosagefrequency, and increased patient compliance. In addition,controlled-release formulations can be used to affect the time of onsetof action or other characteristics, such as blood levels of the drug,and can thus affect the occurrence of side (e.g., adverse) effects.

Most controlled-release formulations are designed to initially releasean amount of drug (active ingredient) that promptly produces the desiredtherapeutic effect, and gradually and continually release of otheramounts of drug to maintain this level of therapeutic or prophylacticeffect over an extended period of time. In order to maintain thisconstant level of drug in the body, the drug must be released from thedosage form at a rate that will replace the amount of drug beingmetabolized and excreted from the body. Controlled-release of an activeingredient can be stimulated by various conditions including, but notlimited to, pH, temperature, enzymes, water, or other physiologicalconditions or compounds.

Parenteral Dosage Forms

Parenteral dosage forms can be administered to patients by variousroutes including, but not limited to, subcutaneous, intravenous, bolusinjection, intramuscular, and intraarterial. Because theiradministration typically bypasses patients' natural defenses againstcontaminants, parenteral dosage forms are preferably sterile or capableof being sterilized prior to administration to a patient. Examples ofparenteral dosage forms include, but are not limited to, solutions readyfor injection, dry products ready to be dissolved or suspended in apharmaceutically acceptable vehicle for injection, suspensions ready forinjection, and emulsions.

Suitable vehicles that can be used to provide parenteral dosage forms ofthe invention are well known to those skilled in the art. Examplesinclude, but are not limited to: Water for Injection USP; aqueousvehicles such as, but not limited to, Sodium Chloride Injection,Ringer's Injection, Dextrose Injection, Dextrose and Sodium ChlorideInjection, and Lactated Ringer's Injection; water-miscible vehicles suchas, but not limited to, ethyl alcohol, polyethylene glycol, andpolypropylene glycol; and non-aqueous vehicles such as, but not limitedto, corn oil, cottonseed oil, peanut oil, sesame oil, ethyl oleate,isopropyl myristate, and benzyl benzoate.

Compounds that increase the solubility of one or more of the activeingredients disclosed herein can also be incorporated into theparenteral dosage forms of the invention.

Transdermal, Topical, and Mucosal Dosage Forms

Transdermal, topical, and mucosal dosage forms of the invention include,but are not limited to, ophthalmic solutions, sprays, aerosols, creams,lotions, ointments, gels, solutions, emulsions, suspensions, or otherforms known to one of skill in the art. See, e.g., Remington'sPharmaceutical Sciences, 16th and 18th eds., Mack Publishing, Easton Pa.(1980 & 1990); and Introduction to Pharmaceutical Dosage Forms, 4th ed.,Lea & Febiger, Philadelphia (1985). Dosage forms suitable for treatingmucosal tissues within the oral cavity can be formulated as mouthwashesor as oral gels. Further, transdermal dosage forms include “reservoirtype” or “matrix type” patches, which can be applied to the skin andworn for a specific period of time to permit the penetration of adesired amount of active ingredients.

Suitable excipients (e.g., carriers and diluents) and other materialsthat can be used to provide transdermal, topical, and mucosal dosageforms encompassed by this invention are well known to those skilled inthe pharmaceutical arts, and depend on the particular tissue to which agiven pharmaceutical composition or dosage form will be applied. Withthat fact in mind, typical excipients include, but are not limited to,water, acetone, ethanol, ethylene glycol, propylene glycol,butane-1,3-diol, isopropyl myristate, isopropyl palmitate, mineral oil,and mixtures thereof to form lotions, tinctures, creams, emulsions, gelsor ointments, which are non-toxic and pharmaceutically acceptable.Moisturizers or humectants can also be added to pharmaceuticalcompositions and dosage forms if desired. Examples of such additionalingredients are well known in the art. See, e.g., Remington'sPharmaceutical Sciences, 16th and 18th eds., Mack Publishing, Easton Pa.(1980 & 1990).

Depending on the specific tissue to be treated, additional componentsmay be used prior to, in conjunction with, or subsequent to treatmentwith active ingredients of the invention. For example, penetrationenhancers can be used to assist in delivering the active ingredients tothe tissue. Suitable penetration enhancers include, but are not limitedto: acetone; various alcohols such as ethanol, oleyl, andtetrahydrofuryl; alkyl sulfoxides such as dimethyl sulfoxide; dimethylacetamide; dimethyl formamide; polyethylene glycol; pyrrolidones such aspolyvinylpyrrolidone; Kollidon grades (Povidone, Polyvidone); urea; andvarious water-soluble or insoluble sugar esters such as Tween 80(polysorbate 80) and Span 60 (sorbitan monostearate).

The pH of a pharmaceutical composition or dosage form, or of the tissueto which the pharmaceutical composition or dosage form is applied, mayalso be adjusted to improve delivery of one or more active ingredients.Similarly, the polarity of a solvent carrier, its ionic strength, ortonicity can be adjusted to improve delivery. Compounds such asstearates can also be added to pharmaceutical compositions or dosageforms to advantageously alter the hydrophilicity or lipophilicity of oneor more active ingredients so as to improve delivery. In this regard,stearates can serve as a lipid vehicle for the formulation, as anemulsifying agent or surfactant, and as a delivery-enhancing orpenetration-enhancing agent. Different salts of the active ingredientscan be used to further adjust the properties of the resultingcomposition.

The present invention will now be illustrated by the followingnon-limiting examples.

EXAMPLES

During an exploration in arctic Alaska for terrestrial and marinemicroorganisms that might contain anticancer constituents, a tundraspecimen on the shore of the Beaufort Sea near Prudhoe Bay was collectedand subsequently found to contain a Gram-positive bacterium identifiedas Kitasatospora sp. After this actinomycete was identified by 16S rRNAgene sequence similarity, it was scaled up in a quarter-strength potatodextrose broth over a seven-thy fermentation period. A dichloromethaneextract of 4 L of broth was concentrated to a residue that inhibitedgrowth of the P388 lymphocytic leukemia and a minipanel of human cancercell lines. For isolation of the anticancer constituents, thefermentation was scaled up to 380 L, and separation was guided by abioassay using both the P388 and human cancer cell line systems. Theresulting extract (3.4 g) was partitioned between 9:1 CH₃OH—water andhexane followed by dilution of the aqueous phase to 3:2 CH₃OH—water andextraction with CH₂Cl₂. Concentration of the latter phase provided theactive fraction (0.50 g, P388 ED₅₀ 0.15 μg/mL). Separation of thisfraction was guided by the P388 lymphocytic leukemia cell line bioassayand was conducted using a series of gel permeation column separations onSephadex-20 followed by partition chromatographic separations, again onLH-20, and finally by reversed-phase high-performance liquidchromatographic separations that led to cyclodepsipeptides 1 (10.8 mg),2 (4.8 mg) and 3 (2.6 mg).

By utilizing a bioassay-(P388 lymphocytic leukemia and a panel of humancancer cell lines) guided separation of a Kitasatospora sp. collectedfrom a tundra soil sample taken at the shore of the Beaufort Sea, wehave isolated three powerful (GI₅₀ to 0.0006 μg/mL) cancer cell growthinhibitors (1-3) and determined their structures. From 380-Lfermentations of Kitasatospora sp. were obtained 2.6 mg of the newcyclodepsipeptide, kitastatin 1 (3), accompanied by respirantin (1, 10.8mg) and its valeryl homologue (2, 4.8 mg). The structures weredetermined by employment of a series of high-resolution mass and 2D-NMRspectroscopic analyses. The stereochemical assignments were based onsubsequent total synthesis of depsipeptides 1, as reported in anaccompanying contribution.

Results and Discussions

In a high-resolution APCI+ mass spectrum, cyclodepsipeptide 1 showed amolecular ion peak at m/z 748.3657 [M+1]⁺ that corresponded to molecularformula C₃₇H₅₃N₃O₁₃. The comprehensive analyses of ¹H-, ¹³C- and 2D-NMRspectra allowed assignment of the following units: lactyl,2-hydroxy-3-methylvaleryl, 4-amino-2,2,6-trimethyl-3-oxoheptanoyl,2-hydroxy-4-methylvaleryl, 2-hydroxy-3-formylaminobenzoyl, and athreonine unit. The connection of the fragments by HMBC-NMR analyses ledto assignment of depsipeptide 1 with unknown stereochemistry, asreported for the Streptomyces sp. constituent 1 by Urushibata⁵ in 1993.

Molecular formula C₃₆H₅₁N₃O₁₃ was assigned to cyclodepsipeptide 2 on thebasis of APCI+ HRMS results, the molecular ion at m/z 734.3500 [M+1]⁺being 14 units (CH₂) less than 1. The NMR proton and carbon assignmentsof cyclodepsipeptide 2 were deduced by comparison with those exhibitedin the NMR spectra of 1. Those comparisons revealed a2-hydroxy-3-methylbutyryl unit in place of the 2-hydroxy-4-methylvalerylunit of 1 and allowed assignment of cyclodepsipeptide 2, previouslydescribed in a 1994 Japanese patent.¹²

The 380-L scale fermentation of Kitasatospora sp. was repeated threetimes in order to obtain sufficient amounts of cyclodepsipeptides 1 and2 for attempts at obtaining crystals for X-ray crystal structuredeterminations. Although suitable crystals were not obtained, one of the380-L fermentations led to isolation of a new cyclodepsipeptidedesignated kitastatin 1 (3), albeit in very low yield (2.6 mg).Kitastatin 1 (3) was obtained as an amorphous powder that gave ahigh-resolution (APCI+) mass spectral molecular ion at m/z 720.3725[M+1]⁺, which corresponds to a formula 28 mass units less than that ofcyclodepsipeptide 1. The ¹H-, ¹³C- and HMQC-NMR spectra of kitastatin 1(Table 1) resembled that of respirantin (1). However, the high-fieldcarbonyl signal corresponding to the aromatic formamide group of 1 wasmissing. That was further confirmed when ¹H-, ¹H-COSY, TOCSY-, and HMBCdata were interpreted and pointed to a 3-amino-2-hydroxy-benzoyl segmentin place of the aromatic formamide as the only structural differencewith cyclodepsipeptide 1. Thus, kitastatin 1 was unequivocally assignedstructure 3.¹³

Because suitable crystallization of cyclodepsipeptides 1-3 was notsuccessful and prevented investigation of the stereochemistry by X-raycrystal structure determinations, we initially focused on high-field 2-DNMR approaches to the stereochemistry. In ROESY-NMR experiments,kitastatin 1 (3) showed cross-peaks related to the ring system atH-2/H-3 (δ_(H) 5.25/6.02), H-9/H-19 (δ_(H) 4.84/1.10) and H-25/NH-9(δ_(H) 2.11/7.53), which suggested a 2S, 3R (or 2R, 3S), 9S and 11S (or9R and 11R) relationship. Similarly, three-cross peaks at H-2/H-3 (δ_(H)5.24/6.03), H-9/H-19 (δ_(H) 4.83/1.09) and H-25/NH-9 (δ_(H) 2.09/7.50)were located in the ROESY spectrum of cyclodepsipeptide 1. While theseNMR experiments were in progress, we were able to unequivocally assignthe stereostructure of 1 and kitastatin 1 (3) as 2S, 3R, 5S, 9S, 11S and13S by our completion of total syntheses.¹³ Since we were unable to makea direct comparison of our cyclodepsipeptides 1 and 2 with authenticsamples previously reported,^(5,12) there still remains some minoruncertainty.

TABLE 1 ¹H- and ¹³C-NMR Spectral Assignments for Kitastatin 1 (3,recorded in CD₂Cl₂, J in Hz)^(a) Posi- δ δ ¹H, HMBC tions ¹³C ¹H ¹H-COSY(C to H) 1-CO 168.0 H-2, H-13 2-CH 55.8 5.25 (dd, 8.5/2.5) NH-2, H-3H-14 3-CH 72.9 6.02 (dq, 7.0/2.5) H-2, H-14 H-14 4-CO 172.3 5-CH 72.64.72 (m) H-15a, H-15b 6-CO 173.7 H-19, H-20 7-C 53.7 H-19, H-20 8-CO208.5 H-9, H-19, H-20 9-CH 56.0 4.84 (dd, NH-9, H-21 H-21 11.0/5.5)10-CO 170.4 H-9, H-11 11-CH 81.4 4.74 (m) H-25 H-26 12-CO 170.2 H-11,H-13, H-29 13-CH 71.6 5.80 (q, 6.5) H-29 H-29 14-CH₃ 16.6 1.36 (d, 6.5)H-3 15-CH₂ 39.8 1.52 (m) H-5, H-15b H-16, H-17 1.72 (m) H-5, H-15a 16-CH24.9 1.74 (m) H-18 17-CH₃ 21.6 0.89 (d, 6.5) H-18 18-CH₃ 22.9 0.94 (d,7.0) H-16 H-17 19-CH₃ 20.0 1.10 (s) H-20 20-CH₃ 24.3 1.27 (s) H-1921-CH₂ 43.3 1.80 (2H, t, 8.5) H-9, H-22 H-9, H-23, H-24 22-CH 25.0 1.64(m) H-21, H-23, H24 H-23, H-24 23-CH₃ 21.1 0.92 (d, 7.0) H-22 H-2124-CH₃ 23.6 0.93 (d, 7.0) H-22 H-21 25-CH 36.9 2.11 (m) H-11, H-26, H27H-11, H-27 26-CH₃ 14.7 0.98 (d, 7.0) H-25 H-27a 27-CH₂ 25.7 1.37 (m)H-25, H-27b, H-27 H-28 1.77 (m) H-27a, H-28 28-CH₃ 10.6 0.97 (t, 7.5)H-27a, H-27b H-27a 29-CH₃ 18.3 1.54 (d, 7.0) H-13 H-13 1′-C 113.3 H-5′2′-C 150.9 H-4′, H-6′ 3′-C 137.0 H-5′ 4′-CH 118.5 6.89 (d, 6.5) H-5′H-6′ 5′-CH 119.3 6.78 (t, 7.5) H-4′, H-6′ 6′-CH 114.6 7.01 (d, 8.0) H-5′H-4′ 7′-CO 171.3 NH-2, H-6′ NH-2 7.08 (d, 8.5) H-2 NH-9 7.53 (d, 9.5)H-9 NH-3′ 4.00 (s, br) ^(a)500 MHz for ¹H NMR, 100 MHz for ¹³C NMR.

To investigate whether minor variations in the fermentation conditionscould lead to a series of new cyclodepsipeptide antineoplastic agents,culture media were modified by adding presumed biochemical precursors,DL-serine, 2-hydroxyl-valeric acid, DL-tyrosine, or shikimic acid.Fermentation conditions as well as bioassay guided isolation techniqueswere otherwise identical. As summarized in Table 2, onlycyclodepsipeptides 1 and 2 were otherwise isolated with the addition ofthe various presumed precursors.

TABLE 2 Results of Fermentation Experiments (Runs A-D)^(a) CH₂Cl₂Fraction and A B C D Cyclodepsipeptide Compounds (mg) (mg) (mg) (mg)CH₂Cl₂ Fraction^(b) 60.0 92.0 185.0 140.0 Cyclodepsipeptide 1 7.0 5.33.7 9.0 Cyclodepsipeptide 2 1.7 2.0 0.9 2.3 ^(a)Run A: culture mediawith addition of DL-serine. Run B: culture media with addition of2-hydroxyvaleric acid. Run C: culture media with addition ofDL-tyrosine. Run D: culture media with addition of shikimic acid.^(b)CH₂Cl₂ extract fraction (from each 380-L fermentation) obtained fromthe CH₂Cl₂/CH₃CHOH—H₂O (3:2) solvent partition isolation step.

The bioassay-directed separation clearly indicated thatcyclodepsipeptides 1-3 are the most important anticancer constituents ofKitasatospora sp. When evaluated against the murine P388 lymphocyticleukemia and six human cancer cell lines, they exhibited extraordinarycancer cell growth inhibitory properties (Table 3).

TABLE 3 Inhibition of the Murine P388 Lymphocytic Leukemia (ED₅₀ μg/mL)and Human Cancer Cell Lines (GI₅₀ μg/mL) by Cyclodepsipeptides 1-3. NCI-Cyclodepsipeptides P388 BXPC-3 MCF-7 SF268 H460 KM20L2 DU-145 1 0.00370.47 0.0006 0.0016 0.0006 0.0006 0.00018 2 0.03 1.2 0.00062 0.0160.00063 0.00058 <0.0001 3 0.045 0.0066 0.004 0.0035 <0.001 0.0024 0.0026

Since the minor structural differences between compounds 1, 2 and 3 didnot greatly affect the cancer cell growth inhibitory activities, itappears that the overall stereochemistry of the macrocyclic lactone andside-chain are of greater importance. Structural modifications ofkitastatin 1¹³ are in progress as well as preclinical development.Interestingly, no previous anticancer activity has been reported forcyclodepsipeptides 1 and 2.^(5,12)

In addition to the human cancer cell line activity, cyclodepsipeptide 1had activity against the pathogenic fungus Cryptococcus neoformans(minimum inhibitory concentration [MIC]=2 μg/ml), and cyclodepsipeptide2 had marginal activity against the opportunistic bacterium Micrococcusluteus (MIC=64 μg/ml). Kitastatin 1 (3) had marginal activity against C.neoformans and Enerococcus faecalis (MIC=64 μg/ml).

General Experimental Procedures.

Solvents used for the chromatographic procedure were redistilled.Sephadex LH-20 employed for gel permeation and partition chromatographywas obtained from Pharmacia Fine Chemicals AB, Upsala, Sweden. Thesilica gel GHLF Uniplates for thin layer chromatography were supplied byAnaltech, Inc., USA. The TLC results were viewed under UV light anddeveloped with ceric sulfate/sulfuric acid (heating for 3 minutes). Theanalytical HPLC was conducted with a Hewlett-Packard model 1100 HPLCcoupled with a diode-array detector and an Elastic Light ScatteredDetector. Reverse-phase HPLC was performed on a ZORBAX SB C18 columnattached to a Waters 600E instrument with a 2487 dual λ absorbancedetector.

The melting points were recorded with a Kofler melting point instrument.The optical rotation data were determined with a Perkin-Elmer 241polarimeter. UV spectra were from a Perkin-Elmer Lambda 3β UV/VISspectrophotometer equipped with a Hewlett-Packard Laser Jet 2000plotter. IR spectra were obtained with an AVATAR 360 FT-IR instrumentwith the sample prepared in CHCl₃ film. High-resolution mass spectrawere obtained with a JEOL LCmate magnetic sector instrument by APCI+with a poly(ethylene glycol) reference. The NMR experiments wereconducted using a Varian Unity INOVA-500 spectrometer operating at 500MHz and 400 MHz for ¹H NMR and 2D NMR and at 100 MHz for ¹³C NMR.

Specimen Collection and Fermentation.

Soil samples were collected in clean plastic bags by one of us (GRP) onthe shore tundra near Prudhoe Bay (Beaufort Sea), Alaska, and shipped byair to our laboratory. Soils were aseptically diluted and spread onquarter-strength potato dextrose agar (Difco) containing soil extract.Kitasatospora sp. was identified by 16S rRNA gene sequence similarity(Accugenix, Newark, Del.). Results from the MicroSeq database based onthe first 500 base pairs of the 16S rRNA gene placed the bacterium inthe genus Kitasatospora sp. (% difference=1.91, confidence level togenus). Isolated colonies were subcultured and fermented in potatodextrose broth/soil extract, and extracts were screened against themurine P388 lymphocytic leukemia cell line and a minipanel of humancancer cell lines. Prior to large-scale fermentation, the P388 and humancancer cell line activity of the actinomycete was determined to beoptimum in quarter-strength potato dextrose broth for seven days. Allactivity peak experiments and large-scale fermentations were performedat room temperature with shaking.

Extraction and Solvent Partition of Kitasatospora sp.

The microbial broth (380 L; February 2003-May 2003) was extracted (3×)with CH₂Cl₂ (½ volume). The CH₂Cl₂ extract was dried (3.4 g) and thenredissolved in 2 L of CH₂Cl₂—H₂O and partitioned (4×) with CH₂Cl₂ (2 Lper pass). The CH₂Cl₂ was quickly removed in vacuo, and the residue wasredissolved in 9:1 CH₃OH—water and partitioned (4×) with hexane. Afterdilution to 3:2 CH₃OH—H₂O, the aqueous phase was partitioned (4×) withCH₂Cl₂ to give 0.5 g of a CH₂Cl₂—soluble fraction (P388 ED₅₀, 0.15μg/mL).

Isolation of Cyclodepsipeptides 1, 2 and 3.

The anticancer CH₂Cl₂ fraction (0.5 g), obtained as described in thepreceding experiment, was passed in CH₃OH through a column of SephadexLH-20. Two resulting bioactive (cancer cell line bioassay) fractionswere combined and chromatographed on a Sephadex LH-20 column inhexane-toluene-methanol (3:1:1) as eluent, which led to theconcentration into one fraction of the inhibitory activity (57 mg, P3880.02 μg/mL). Further separation of the active fraction was performedusing reverse-phase HPLC. Initially, analytical HPLC of the fraction wasconducted on a HP1100 series instrument with both ELSD and UV detectorsto locate the target peaks. The fraction was then separated bysemi-preparative HPLC on a Waters instrument with a ZORBAX SB C18 column(9.6×250 mm) in acetonitrile-water (40% to 90% in 45 minutes) at 4mL/minute flow rate. Cyclodepsipeptides 1, 2 and 3 were obtained byconcentration of the eluting fractions with peaks at retention times of42.5, 40 and 45 min, respectively.

The experimental results summarized in Table 2 were obtained byemployment of the preceding procedure.

Cyclodepsipeptide 1.

Colorless amorphous powder (10.8 mg): mp 118-120° C.; ¹H NMR (CD₂Cl₂,500 MHz) δ 12.61 (1H, s, 2′-OH), 8.54 (1H, d, J=6.0 Hz, H-4′), 8.47 (1H,s, H-8′), 7.92 (1H, s, 3′-NH), 7.50 (1H, d, J=7.5 Hz, 9-NH), 7.40 (1H,d, J=6.0 Hz, H-6′), 7.16 (1H, d=7.0 Hz, 2-NH), 6.97 (1H, t, J=6.0 Hz,H-5′), 6.03 (1H, m, H-3), 5.80 (1H, q, J=6.0 Hz, H-13), 5.24 (1H, dd,J=1.6, 7.0 Hz, H-2), 4.83 (1H, m, H-9), 4.73 (1H, m, H-11), 4.71 (1H, m,H-5), 2.09 (1H, m, H-25), 1.80 (2H, m, H-21), 1.76 (1H, m, H-27b), 1.70(1H, m, H-16), 1.68 (1H, m, H-15b), 1.62 (1H, m, H-22), 1.54 (1H, m,H-15a), 1.54 (3H, d, J=6.0 Hz, H-29), 1.36 (3H, d, J=6.0 Hz, H-14), 1.33(1H, m, H-27a), 1.27 (3H, s, H-20), 1.09 (3H, s, H-19), 0.96 (3H, d,J=6.0 Hz, H-26), 0.95 (3H, t, J=6.0 Hz, H-28), 0.93 (3H, d, J=6.0 Hz,H-18), 0.92 (3H, d, J=6.0 Hz, H-23), 0.91 (3H, d, J=6.0 Hz, H-24), 0.89(3H, d, J=6.0 Hz, H-17), ¹³C NMR (CD₂Cl₂, 100 MHz) δ 208.0(C-8),173.7(C-6), 172.3(C-4), 170.7(C-7′), 170.4(C-10), 170.1(C-12),167.8(C-1), 159.3(C-8′), 150.9(C-2′), 127.9(C-3′), 125.0(C-4′),120.7(C-6′), 119.2(C-5′), 113.3(C-1′), 81.4(C-11), 72.7(C-3), 72.6(C-5),71.7(C-13), 56.8(C-9), 56.0(C-2), 54.2(C-7), 43.3(C-21), 39.7(C-15),36.8(C-25), 25.7(C-27), 24.9(C-16), 24.8(C-22), 24.3(C-20), 23.6(C-23),23.0(C-18), 21.5(C-17), 21.0(C-24), 20.0(C-19), 18.3(C-29), 16.6(C-14),14.5(C-26), 10.6(C-28); HRMS (APCI+) m/z 748.3691 [M+H]⁺ (calcd forC₃₇H₅₄N₃O₁₃, 748.3657).

Cyclodepsipeptide 2.

Colorless amorphous powder (4.8 mg): mp 117-120° C.; ¹H NMR (CD₂Cl₂, 400MHz) δ 12.62 (1H, s, 4′-OH), 8.53 (1H, d, J=8.0 Hz, H-4′), 8.50 (1H, s,H-8′), 8.02 (1H, s, 3′-NH), 7.52 (1H, d, J=10.0 Hz, 9-NH), 7.43 (1H, d,J=8.0 Hz, H-6′), 7.18 (1H, d, J=8.0 Hz, 2-NH), 6.99 (1H, t, J=7.6 Hz,H-5′), 6.02 (1H, m, H-3), 5.82 (1H, q, J=7.2 Hz, H-13), 5.26 (1H, d,J=8.8 Hz, H-2), 4.85 (1H, m, H-9), 4.77 (1H, m, H-11), 4.54 (1H, m,H-5), 2.12 (1H, m, H-15), 2.10 (1H, m, H-24), 1.83 (2H, t, J=6.0 Hz,H-20), 1.75 (1H, m, H-26b), 1.62 (1H, m, H-21), 1.56 (3H, d, J=6.4 Hz,H-28), 1.39 (3H, d, J=6.4 Hz, H-14), 1.37 (1H, m, H-26a), 1.29 (3H, s,H-19), 1.11 (3H, s, H-18), 0.98 (3H, d, J=6.4 Hz, H-17), 0.98 (3H, d,J=6.4 Hz, H-25), 0.97 (3H, t, J=6.4 Hz, H-27), 0.95 (3H, d, J=6.4 Hz,H-16), 0.92 (3H, d, J=6.4 Hz, H-23), 0.92 (3H, d, J=6.4 Hz, H-24); ¹³CNMR (CD₂Cl₂, 100 MHz) δ. 207.5(C-8), 173.6(C-6), 170.9(C-4),170.9(C-7′), 170.6(C-10), 170.0(C-12), 167.7(C-1), 159.5(C-8′),150.8(C-2′), 127.9(C-3′), 125.0(C-4′), 120.7(C-6′), 119.1(C-5′),113.5(C-1′), 81.0(C-11), 78.3(C-5), 72.7(C-3), 71.6(C-13), 56.7(C-9),55.9(C-2), 53.8(C-7), 42.8(C-20), 36.8(C-24), 30.3 (C-15), 25.4(C-26),24.8(C-19), 24.1(C-21), 23.6(C-23), 20.0(C-22), 19.8(C-18), 18.4(C-17),18.1(C-28), 17.7(C-16), 16.6(C-14), 14.4(C-25), 10.4(C-27); HRMS (APCI+)m/z 734.351 [M+H]⁺ (calcd for C₃₆H₅₂N₃O₁₃, 734.3500).

Cyclodepsipeptide 3.

Colorless amorphous powder: mp 126-129° C.; [α]²⁴ _(D)−10 (c 0.07,CH₃OH); UV (CH₃OH) λ_(max) 231, 328 nm; IR (CHCl₃), v. 1745, 1712, 1665,1644, 1502 and 1525 cm⁻¹; HRMS (APCI+) m/z 720.3725 [M+H]⁺ (calcd forC₃₆H₅₄N₃O₁₂, 720.3708); ¹H and ¹³C NMR data see Table 1.

Antimicrobial Susceptibility Testing

Cyclodepsipeptides 1 and 2 were screened against the bacteriaStenotrophomonas maltophilia ATCC 13637, Micrococcus luteus Presque Isle456, Staphylococcus aureus ATCC 29213, Escherichia coli ATCC 25922,Enterobacter cloacae ATCC 13047, Enterococcus faecalis ATCC 29212,Streptococcus pneumoniae ATCC 6303, Neisseria gonorrhoeae ATCC 49226,and the fungi Candida albicans ATCC 90028 and Cryptococcus neoformansATCC 90112, according to established broth microdilution susceptibilityassays.^(15,16) Owing to a paucity of material, compound 2 was testedagainst S. maltophilia, M. luteus, S. aureus, E. coli and C. albicansonly. Compounds were reconstituted in a small volume of sterile DMSO anddiluted in the appropriate media immediately prior to susceptibilityexperiments. The minimum inhibitory concentration was defined as thelowest concentration of compound that inhibited all visible growth ofthe test organism (optically clear). Assays were repeated on separatedays.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the invention that others can, by applyingcurrent knowledge, readily modify and/or adapt for various applicationssuch specific embodiments without undue experimentation and withoutdeparting from the generic concept, and, therefore, such adaptations andmodifications should and are intended to be comprehended within themeaning and range of equivalents of the disclosed embodiments. It is tobe understood that the phraseology or terminology employed herein is forthe purpose of description and not of limitation. The means, materials,and steps for carrying out various disclosed chemical structures andfunctions may take a variety of alternative forms without departing fromthe invention.

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What is claimed is:
 1. A method of inhibiting carcinoma cell growth in ahost inflicted therewith comprising administering to a host atherapeutically effective amount of a compound, wherein the compound hasthe structural formula:


2. The method of claim 1, wherein the compound is administered in apharmaceutical acceptable carrier and is administered in an amount offrom about 1 mg to about 2000 mg.
 3. The method of claim 2, wherein thecompound is administered in an amount of from about 100 mg to about 500mg.
 4. The method of claim 1, wherein the compound is administeredintravenous in an amount between 0.01 to about 20 mg/kg; intramuscularin an amount between 0.1 to about 50 mg/kg; orally in an amount 0.05 toabout 100 mg/kg; intranasal instillation in an amount between 0.5 toabout 100 mg/kg; or aerosol in an amount between 0.5 to about 100 mg/kgof host body weight.
 5. A method of inhibiting carcinoma cell growth ina host inflicted therewith comprising administering to a host atherapeutically effective amount of a compound, wherein the compound hasthe structural formula: